Ritanserin (R 55667)

Ritanserin (R 55667) is a highly potent, selective, orally active, and long-acting antagonist of 5-HT2 receptor with an IC50 of 0.9 nM. It exhibits minimal activity at H1, D2, and adrenergic receptors and enhances midbrain dopamine neuron activity by blocking 5-HT2-mediated inhibition.